MM74C928N

4位计数器与复用 4-Digit Counters with Multiplexed

General Description

The MM74C925, MM74C926, MM74C927 and MM74C928 CMOS counters consist of a 4-digit counter, an internal out put latch, NPN output sourcing drivers for a 7-segment display, and an internal multiplexing circuitry with four multiplexing outputs. The multiplexing circuit has its own

free-running oscillator, and requires no external clock. The counters advance on negative edge of clock. A HIGH signal on the Reset input will reset the counter to zero, and reset the carry-out LOW. A LOW signal on the Latch Enable input will latch the number in the counters into the

internal output latches. A HIGH signal on Display Select input will select the number in the counter to be displayed; a LOW level signal on the Display Select will select the number in the output latch to be displayed.

Features

■Wide supply voltage range: 3V to 6V

■Guaranteed noise margin: 1V

■High noise immunity: 0.45 VCCtyp.

■High segment sourcing current: 40 mA

    @ VCC −1.6V, VCC =5V

■Internal multiplexing circuitry